Q44. Which three are true about the Oracle Optimizer?
A. It obeys all hints.
B. It updates stale object statistics in the Data Dictionary.
C. It can only use SQL Plan Directives tied to the SQL statement for which a plan is being generated.
D. It can re-optimize execution plans after previous executions detect suboptimal plans.
E. It considers object statistics when generating execution plans for SQL statements.
F. It considers the filters in WHERE clauses when generating execution plans for SQL statements.
Answer: DEF
Oracle Optimizer has the capability to re-optimize execution plans based on feedback and performance data from previous executions. This helps in adapting to changing data distributions and query patterns.
The Oracle Optimizer takes into account object statistics (such as table and index statistics) when generating execution plans. These statistics provide information about the data distribution and help the optimizer choose efficient access paths.
The Oracle Optimizer considers the filters specified in the WHERE clauses of SQL statements when generating execution plans. This involves evaluating the selectivity of predicates and choosing an optimal plan based on the available indexes and access paths.